This invention relates to a magnetic tape cartridge for an audio equipment, a video equipment or the like, and more particularly to a magnetic tape cartridge including a magnetic tape arranged in a casing for recording and playing-back.
Generally, in a magnetic tape cartridge of such type, a magnetic tape is arranged in a casing while being kept contacted with tape guides for guiding traveling of the tape. Thus, in use of the magnetic tape cartridge, the magnetic tape travels while being contacted with the surface of each of the tape guides, so that the tape guides are conventionally made of a metal material exhibiting rub resistance and resistance to wear. Unfortunately, this causes the processing and manufacturing costs of the cartridge to be significantly increased. In order to avoid the disadvantage, a synthetic resin material such as polyacetal resin, polyamide resin, ultra-high-molecular-weight polyethylene or the like is used for the tape guides so as to permit them to exhibit satisfactory rub resistance and resistance to wear for a long period of time, as disclosed in Japanese Utility Model Publication No. 23834/1985.
More particularly, the tape guides are made of a synthetic resin material mainly consisting of polyacetal, because it facilitates formation of the tape guides and is not costly as compared with a metal material. Unfortunately, the result of an endurance traveling test which the inventors carried out on tape guides made of such a synthetic material revealed that the material tends to cause the tape guides to produce powdered dust by wearing due to contacting with the magnetic tape over a long period of time, which then adheres to the surface of a magnetic tape, to thereby lead to dropout of data recorded on the tape. Also, the wearing of the tape guides causes scraping of the tape. In particular, a conventional magnetic tape which is made of a polyester film having a magnetic layer deposited thereon and of which the surface contacted with the tape guides is 0.010 to 0.014 .mu.m in roughness is significantly increased in frictional resistance to the tape guides made of a synthetic resin material such as the above-described material mainly consisting of polyacetal, to thereby increase rewinding torque and deteriorate jitter (reproduced image), leading to lowering of the quality.